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Members of Congress reveal their preferences on an issue, not only in how they vote, but also how they spend their time. I introduce and validate a new measure of Congressional engagement in national defense, based on the amount of time and legislative energy a member spends on defense issues. I demonstrate the utility of this index through the reexamination of two key puzzles in the literature on Congressional defense preferences: how veterans and members with military interests vote relative to their peers. Using the National Defense Engagement Index (NDEI) I find that both veterans and members who have military industry in their districts are much more likely to be engaged with defense than other members of Congress. These results help to resolve discrepancies in previous literature and suggest the benefit of investigating member engagement as a key part of research on Congressional behavior. [ABSTRACT FROM AUTHOR]

To reduce bird collisions on wind turbines, Automatic Detection Systems have been developed to locate approaching birds and trigger turbines to slowdown to 2–3 rotations per minute (rpm). However, it is unknown whether birds can detect this reduced speed and avoid the turbine. We conducted an operant conditioning experiment on domestic doves (Streptopelia roseogrisea) and Harris's hawks (Parabuteo unicinctus) to assess their ability to discriminate between stationary and rotating miniature wind turbines, depending on the rotation speed and the contrast between the white blades and the background (only for doves for the latter). At high contrast, regardless of the speed tested, hawks were able to differentiate between the rotating and stationary turbines, while doves were not able to discriminate the slow‐rotating turbine (3 rpm) from the stationary one. The discrimination threshold increased to 8 rpm for the doves when the contrast was reduced. Our results suggest that the residual wind turbine speed of 2–3 rpm may not be detected by all bird species under all environmental conditions. Increasing the contrast between wind turbines and their environment may improve the detection of low‐speed rotation by some birds, otherwise, complete turbine shutdown should be recommended. [ABSTRACT FROM AUTHOR]

Interbreeding of related forms following anthropogenic activity can lead to genomic homogenization, contributing to decreasing biodiversity. Assessing spatiotemporal variation in the extent of introgression is important for conservation but can be expensive and logistically complex. The Rock Dove Columba livia is threatened by interbreeding with its feral conspecific and it is difficult to identify wild birds when wild, feral and mixed populations exist. Here, using British and Irish populations, I assess whether the proportion of birds with wild type plumage corresponds to distinctive head morphotypes differing between Rock Doves and feral pigeons, and whether plumage can be used to identify Rock Dove flocks and infer the extent of hybridization. I also determine whether plumage proportions have changed since a prior study was carried out in the 1960s. I show that flocks in which > 75% of individuals have wild type plumage consist of Rock Doves, as determined by head morphotype. Plumage proportions vary geographically, corroborating known genomic assessments of Scottish and Irish Rock Doves. Finally, the number of birds with aberrant plumages has increased since the 1960s, even in regions where no such birds were identified previously. This highlights the value of the Rock Dove as a current case study with which to explore the process of extinction by hybridization. [ABSTRACT FROM AUTHOR]

The European Turtle Dove Streptopelia turtur is a trans‐Saharan migratory species that has been declining for decades. This study reports nesting habitat, nest‐site characteristics, nesting success (38.6%) and productivity (2.40 young per pair per season) of European Turtle Doves radiotracked in a deciduous forest of western France. A matrix population model based on our results suggests that the average productivity reported would need to be increased by about 0.18 additional young per pair to achieve a population growth rate equal to one. However, elasticity analysis suggests that increasing adult survival would have the highest impact on population growth compared with increased productivity or first‐year survival. [ABSTRACT FROM AUTHOR]

The current study was conducted to investigate the efficacy and stability of D‐limonene (DL) and its nanoemulsion (DLN) against pigeon feather lice (Columbicola columbae) and their mode of action. DL pure form and DLN were prepared and characterized freshly and after storage for 50 days. In vitro bioassay on live lice was conducted with different concentrations of DL, DLN, and deltamethrin (DM). The results revealed significant mortality rates in the DL‐, DLN‐, DM‐treated groups when compared with the control (p < 0.05). The scanning electron micrographs of lice treated with DL and DLN revealed collapsed bodies with destruction in the cuticle of the mouthparts and damaged antennae. The 50 days stored DLN showed stability in their effectiveness when compared with the freshly prepared formulation. DL and DLN caused significant inhibition (p ≤ 0.05) in acetylcholinesterase activity (AchE). Malondialdehyde level (MDA) was significantly increased while glutathione was significantly decreased in DL‐ and DLN‐treated lice. In conclusion, DL and DLN have significant lousicidal activities. DLN showed better stability than DL after storage for 50 days. In addition, the mode of action of DL may associate with its effect on the cuticle of the lice body, inhibition of AchE, and increasing oxidative stress in the treated lice. [ABSTRACT FROM AUTHOR]

The identification of migration dates and wintering zones for migratory birds are key elements for the understanding of the Afro‐Palearctic migration system. From 2015 to 2022, a large‐scale survey of Turtle Doves Streptopelia turtur, a vulnerable species, was established in Northwest Africa, including Morocco, Algeria, and Tunisia. We monitored migration dates and wintering individuals using the line‐transect method. We found that Turtle Doves arrived in the last week of March and left the North African region in mid‐October. Compared with Morocco, Doves arrived significantly earlier in Algeria and Tunisia. Moreover, Doves were discovered wintering on nine Northwest African sites, from October to February, where individuals feed in groups. We found that the occurrence probability of wintering Turtle Doves decreased significantly with increasing temperature and rainfall. Birds wintered most often close to wetlands since the overwintering probability decreased with the increasing distance from the recording area to the nearest water body. These are the first and only detailed findings on the migration phenology of the globally vulnerable Turtle Dove in north western Africa. [ABSTRACT FROM AUTHOR]

Understanding the frequency, spatiotemporal dynamics and impacts of parasite coinfections is fundamental to developing control measures and predicting disease impacts. The European turtle dove (Streptopelia turtur) is one of Europe's most threatened bird species. High prevalence of infection by the protozoan parasite Trichomonas gallinae has previously been identified, but the role of this and other coinfecting parasites in turtle dove declines remains unclear. Using a high‐throughput sequencing approach, we identified seven strains of T. gallinae, including two novel strains, from ITS1/5.8S/ITS2 ribosomal sequences in turtle doves on breeding and wintering grounds, with further intrastrain variation and four novel subtypes revealed by the iron‐hydrogenase gene. High spatiotemporal turnover was observed in T. gallinae strain composition, and infection was prevalent in all populations (89%–100%). Coinfection by multiple Trichomonas strains was rarer than expected (1% observed compared to 38.6% expected), suggesting either within‐host competition, or high mortality of coinfected individuals. In contrast, coinfection by multiple haemosporidians was common (43%), as was coinfection by haemosporidians and T. gallinae (90%), with positive associations between strains of T. gallinae and Leucocytozoon suggesting a mechanism such as parasite‐induced immune modulation. We found no evidence for negative associations between coinfections and host body condition. We suggest that longitudinal studies involving the recapture and investigation of infection status of individuals over their lifespan are crucial to understand the epidemiology of coinfections in natural populations. [ABSTRACT FROM AUTHOR]

European Turtle Doves Streptopelia turtur have experienced a sharp decline in population numbers over past decades. Much uncertainty exists about the main cause or causes. Several pressures have been suggested, but because they affect different stages of the life cycle of the Turtle Dove, it is difficult to compare their contributions to the population decline. Here we applied a full life cycle approach to study how different pressures may have resulted in the decline. This was achieved by combining a review of existing literature on possible threats, pressures and the vital rates they concerned, with the analysis of an age‐structured matrix model. The population model was parameterized using estimates from a mark–recapture analysis and supplemented with vital rate estimates from the literature. Comparison with a Life Table Response Experiment (LTRE) was used to determine whether the Turtle Dove literature focuses on those vital rates in which the most important changes have taken place over time. The population model projected a similar decline to that observed in population counts. The LTRE analysis showed that declines in the number of clutches (halved since the 1960s) and in juvenile survival (relative annual rate of change of –1.33% since the 1950s) contributed most to the decline in the projected population growth rate. Although these vital rates are often reported as possible causes of population decline, the reviewed studies often focused on specific reproductive stages, such as egg survival or nestling survival, which did not show a large temporal change. Thus, there is a partial mismatch between our modelling results and the focus in the literature. Juvenile survival is thought to be affected by hunting, degradation of wintering habitat and infection with Trichomonas gallinae, and loss of foraging habitat seems to affect the number of clutches. The focus of conservation measures should therefore be on these threats and pressures. The first steps have already been taken with the completion of the international single species action plan for the conservation of the Turtle Dove and the implementation of the first conservation measures on the breeding grounds. [ABSTRACT FROM AUTHOR]

We present a new methodology to partition different sources of behavior change within a selectionist framework based on the Price equation-the multilevel model of behavioral selection. The multilevel model of behavioral selection provides a theoretical background to describe behavior change in terms of operant selection. Operant selection is formally captured by the covariance-based law of effect and accounts for all changes in individual behavior that involve a covariance between behavior and predictors of evolutionary fitness (e.g., food). In this article, we show how the covariance-based law of effect may be applied to different components of operant behavior (e.g., allocation, speed, and accuracy of responding), thereby providing quantitative estimates for various selection effects affecting behavior change using data from a published learning experiment with pigeons., (© 2024 The Author(s). Journal of the Experimental Analysis of Behavior published by Wiley Periodicals LLC on behalf of Society for the Experimental Analysis of Behavior.)

Avian malaria (Plasmodium) and related genera (Haemoproteus and Leucocytozoon) are diverse and widespread parasites. Despite the extent of knowledge on avian haemosporidian parasites, information about domestic and wild bird's blood parasites is overall insufficient in Iran. Prevalence of the haemosporidian parasites' and phylogenetic relationship of lineages are studied by using molecular and morphological results of 152 examined hosts belonging to 17 species. Molecular analysis for haemosporidian detections demonstrated overall prevalence 22.36%. Inspected hosts mostly belonging to Common Pigeons (Columba livia) parasitized by Haemoproteus spp., and Hooded Crows (Corvus cornix) and Carrion Crow (C. corone) were identified as hosting Plasmodium spp. Detected lineages COLIV03, COQUI05, LINN01, ROFI04 and SGS01 are identified as new reports from Iran. We detected no evidence of Leucocytozoon lineages, while the high prevalence of H. columbae was found in Common Pigeons. Such investigation on avian blood parasites contributes to providing new information on the prevalence, epidemiology and geographical distribution of haemosporidian parasites circulating in domestic, pets and wild birds. [ABSTRACT FROM AUTHOR]

Imbert–Fedorov (IF) effects of a polarized laser beam reflected from a dove prism/indium tin oxide (ITO) interface in the presence of electric and thermal fields are studied using a slit‐beam profiler and Stokes polarimeters. The IF effects of the polarized laser beams are primarily influenced by an electric field when the external direct current (DC) voltage is below 1.0 V, and it is mainly influenced by the thermal field when the external DC voltage changes from 1.0 to 4.0 V. The results exhibit a high resolution of 3 × 10−3 °C, due to the variation of the right‐ and left‐circular polarization properties of the reflected linearly polarized laser beams. In view of this influence of electric and thermal fields on IF effects, the results can be applied in polarization optics, temperature sensing, and light manipulation. [ABSTRACT FROM AUTHOR]

Can simple choice conditional-discrimination choice be accounted for by recent quantitative models of combined stimulus and reinforcer control? In Experiment 1, two sets of five blackout durations, one using shorter intervals and one using longer intervals, conditionally signaled which subsequent choice response might provide food. In seven conditions, the distribution of blackout durations across the sets was varied. An updated version of the generalization-across-dimensions model nicely described the way that choice changed across durations. In Experiment 2, just two blackout durations acted as the conditional stimuli and the durations were varied over 10 conditions. The parameters of the model obtained in Experiment 1 failed adequately to predict choice in Experiment 2, but the model again fitted the data nicely. The failure to predict the Experiment 2 data from the Experiment 1 parameters occurred because in Experiment 1 differential control by reinforcer locations progressively decreased with blackout durations, whereas in Experiment 2 this control remained constant. These experiments extend the ability of the model to describe data from procedures based on concurrent schedules in which reinforcer ratios reverse at fixed times to those from conditional-discrimination procedures. Further research is needed to understand why control by reinforcer location differed between the two experiments., (© 2024 The Authors. Journal of the Experimental Analysis of Behavior published by Wiley Periodicals LLC on behalf of Society for the Experimental Analysis of Behavior.)

Experimental analyses of coordinated responding (i.e., cooperation) have been derived from a procedure described by Skinner (1962) in which reinforcers were delivered to a pair of subjects (a dyad) if both responded within a short interval, thus satisfying a coordination contingency. Although it has been suggested that this contingency enhances rates of temporally coordinated responding, limitations of past experiments have raised questions concerning this conclusion. The present experiments addressed some of these limitations by holding the schedule of reinforcement (Experiment 1: fixed ratio 1; Experiment 2; variable interval 20 s) constant across phases and between dyad members and by varying, in different conditions, the number of response keys (one to three) across which coordination could occur. Greater percentages of coordinated responding occurred under the coordinated-reinforcement phases than under independent-reinforcement phases in most conditions. The one exception during the one-key condition of Experiment 1 appeared to be a consequence of variability introduced by the independent-reinforcement phase procedure. Furthermore, coordination percentages decreased with increasing response options under both schedules. These results confirm and extend the finding that coordination contingencies control higher rates of temporally coordinated responding than independent-reinforcement contingencies do., (© 2024 Society for the Experimental Analysis of Behavior.)

Behavioral momentum theory (BMT) provides a theoretical and methodological framework for understanding how differentially maintained operant responding resists disruption. A common way to test operant resistance involves contingencies with suppressive effects, such as extinction or prefeeding. Other contingencies with known suppressive effects, such as response-cost procedures arranged as point-loss or increases in response force, remain untested as disruptive events within the BMT framework. In the present set of three experiments, responding of humans was maintained by point accumulation programmed according to a multiple variable-interval (VI) VI schedule with different reinforcement rates in either of two components. Subsequently, subtracting a point following each response (Experiment 1) or increasing the force required for the response to be registered (Experiments 2 and 3 decreased response rates, but responding was less disrupted in the component associated with the higher reinforcement rate. The point-loss contingency and increased response force similarly affected response rates by suppressing responding and human persistence, replicating previous findings with humans and nonhuman animals when other types of disruptive events (e.g., extinction and prefeeding) were investigated. The present findings moreover extend the generality of the effects of reinforcement rate on persistence, and thus BMT, extending the analysis of resistance to two well-known manipulations used to reduce responding in the experimental analysis of behavior., (© 2023 Society for the Experimental Analysis of Behavior.)

Understanding how land cover and potential competition with invasive species shape patterns of occupancy, extirpation, and colonization of native species across a landscape can help target management for declining native populations. Mourning dove (Zenaida macroura) populations have declined throughout the United States from 1965–2015. The expansion of the Eurasian collared‐dove (Streptopelia decaocto), an introduced species with similar food preferences, may further threaten mourning dove populations. We analyzed data from 2009–2016 from a large‐scale monitoring program in the Western Great Plains of the United States in a 2‐species occupancy model to assess the effects of collared‐doves on mourning dove distributions, while accounting for imperfect detection and variation in land cover across the landscape. Mourning dove occupancy was stable or increasing across our study area, and despite overlap in resource use and co‐occurrence between mourning doves and Eurasian collared‐doves, we found no evidence that collared‐doves are extirpating mourning doves from preferred habitat during the breeding season. © 2020 The Wildlife Society. We investigated whether Eurasian collared‐doves have affected the distribution of mourning doves in the western Great Plains of the United States. Both species choose similar land cover types and collared‐doves do not seem to be influencing landscape‐level occurrence of mourning doves within our study area. [ABSTRACT FROM AUTHOR]

Range expansions require the dispersal of individual organisms, but dispersal behavior is notoriously difficult to study. Eurasian collared‐doves have colonized both Europe and North America this century, with both initial invasions proceeding northwestward via 'jump' dispersal. The European population has reached carrying capacity, but in the Americas, where exponential population growth continues, little is known about dispersal behavior. I queried citizen science field notes to investigate Eurasian collared‐dove dispersal behavior in North America along the Pacific Ocean, a natural barrier to northwestward landbird dispersal. I examined coastal and pelagic records of Eurasian collared‐doves to determine the seasonality and directionality of dispersal flights and to assess changes in the frequency of dispersal‐related behavior across years. Most reports of Eurasian collared‐doves flying in flocks along the coast and most pelagic sightings were in March–May, mirroring the spring natal dispersal documented during the European invasion. Almost all spring coastal flocks were flying north, consistent with the overall northwestward direction of the initial North American invasion and northward deflection of northwest‐bound birds upon encountering the Pacific Ocean. Spring flying flock observations showed no significant change in frequency from 2010 to 2018 after controlling for overall increases in spring collared‐dove reports. This refined understanding of Eurasian collared‐dove dispersal behavior informs full life cycle management of this rapidly increasing invader in the Americas, raises new questions about evolutionary mechanisms driving this spectacular invasion, and illustrates the potential power of citizen science field notes for documenting dispersal behavior, a longstanding challenge in ecology. [ABSTRACT FROM AUTHOR]

Three pigeon dyads were exposed to a two-component multiple schedule comprised of two tandem variable-interval 30-s interresponse time (IRT) > 3-s schedules in the presence of different stimuli. Pecks to keys by both pigeons of a dyad occurring within 500 ms of one another were required for reinforcement under one tandem schedule (the coordination component), and such coordinated responses were not required under the other (the control component). The terminal link of each schedule ensured that the reinforced coordination response was an IRT > 3 s. Rates of coordinated IRTs > 3 s and total rates of coordinated responses (composed of IRTs > 3 s and IRTs ≤ 3 s) were higher in the coordination components than in either of two different control components in which coordination was not required for reinforcement. This difference in coordinated responses in the presence and absence of the coordination requirement under stimulus control transitorily deteriorated and then was reestablished when the relation between the stimulus and the coordination contingency or its absence was reversed. The results show coordinated responding to function as a discriminated social operant., (© 2023 Society for the Experimental Analysis of Behavior.)

We investigated the effects of differential and nondifferential reinforcers on divided control by compound-stimulus dimensions. Six pigeons responded in a delayed matching-to-sample procedure in which a blue or yellow sample stimulus flashed on/off at a fast or slow rate, and subjects reported its color or alternation frequency. The dimension to report was unsignaled (Phase 1) or signaled (Phase 2). Correct responses were reinforced with a probability of .70, and the probability of reinforcers for errors varied across conditions. Comparison choice depended on reinforcer ratios for correct and incorrect responding; as the frequency of error reinforcers according to a dimension increased, control (measured by log d) by that dimension decreased and control by the other dimension increased. Davison and Nevin's (1999) model described data when the dimension to report was unsignaled, whereas model fits were poorer when it was signaled, perhaps due to carryover between conditions. We are the first to test this quantitative model of divided control with reinforcers for errors and when the dimension to report is signaled; hence, further research is needed to establish the model's generality. We question whether divided stimulus control is dimensional and suggest it may instead reflect joint control by compound stimuli and reinforcer ratios., (© 2023 The Authors. Journal of the Experimental Analysis of Behavior published by Wiley Periodicals LLC on behalf of Society for the Experimental Analysis of Behavior.)

In separate chambers, responding by two pairs of pigeons was reinforced under concurrent random-ratio schedules of reinforcement. For each pair, the birds' schedules were coupled in such a manner that left- and right-key reinforcement probabilities were determined by the key being pecked by the other pigeon of the pair. In this way, a reinforcement matrix, like that of the popular Prisoner's Dilemma game of game theory, was created. The responding of all subjects soon gravitated to the choice combination identified by the mathematician John Nash as the equilibrium of the Prisoner's Dilemma game. This was found both before and after reversal of contingencies on the keys. In a second experiment, with a single pair of pigeons, stimuli signaling the choice of the paired pigeon had little lasting effect: responding again gravitated to the game's equilibrium. The results affirm earlier findings, demonstrating that Skinner's principle of positive reinforcement, together with Nashian mathematics, entirely accounts for iterative game-theoretic behavior. They extend these findings to the so-called free operant: to schedules of reinforcement in which responding is not constrained by stimulus-response sequencing (i.e., a trials procedure). The coupled schedule of reinforcement introduced here offers significant promise for the experimental analysis of economic and social behaviors., (© 2023 Society for the Experimental Analysis of Behavior.)

Abstract: Dietary changes linked to the availability of anthropogenic food resources can have complex implications for species and ecosystems, especially when species are in decline. Here, we use recently developed primers targeting the ITS2 region of plants to characterize diet from faecal samples of four UK columbids, with particular focus on the European turtle dove (Streptopelia turtur), a rapidly declining obligate granivore. We examine dietary overlap between species (potential competition), associations with body condition in turtle doves and spatiotemporal variation in diet. We identified 143 taxonomic units, of which we classified 55% to species, another 34% to genus and the remaining 11% to family. We found significant dietary overlap between all columbid species, with the highest between turtle doves and stock doves (Columba oenas), then between turtle doves and woodpigeons (Columba palumbus). The lowest overlap was between woodpigeons and collared doves (Streptopelia decaocto). We show considerable change in columbid diets compared to previous studies, probably reflecting opportunistic foraging behaviour by columbids within a highly anthropogenically modified landscape, although our data for nonturtle doves should be considered preliminary. Nestling turtle doves in better condition had a higher dietary proportion of taxonomic units from natural arable plant species and a lower proportion of taxonomic units from anthropogenic food resources such as garden bird seed mixes and brassicas. This suggests that breeding ground conservation strategies for turtle doves should include provision of anthropogenic seeds for adults early in the breeding season, coupled with habitat rich in accessible seeds from arable plants once chicks have hatched. [ABSTRACT FROM AUTHOR]

Ten apparently healthy, adult laughing doves were used to document detailed histological, histochemical and surface ultrastructural features of the nasal cavity and to investigate the structure-function relationship of the nasal cavity in this species. We observed that the nasal cavity of the laughing dove was composed of three main regions: nasal vestibule, respiratory and olfactory. Each region presented a characteristic epithelial lining. The epithelium varied along the nasal vestibule from keratinized stratified squamous rostrally to non-keratinized stratified squamous in the middle and stratified cuboidal in the caudal region of the nasal vestibule. The respiratory region was lined with pseudostratified columnar epithelium and was initially devoid of both goblet cells and cilia, but cilia then appeared and increased gradually in number close to the olfactory region. The caudal part of the respiratory region presented a stratified cuboidal epithelium. Strong alcianophilic, intra-epithelial mucous glands were identified, starting at the caudal region of the nasal vestibule and extended into the respiratory region. The olfactory region was lined with a pseudostratified epithelium that consisted of three different cell types: olfactory, support cells and basal cells. In conclusion, the current investigation presents new information concerning the histological, histochemical and ultrastructural features of the laughing dove's nasal cavity. Furthermore, the findings of this study may prove to be a valuable contribution to the avian histology and pathology literature. [ABSTRACT FROM AUTHOR]

DNA barcodes are widely used in taxonomy, systematics, species identification, food safety, and forensic science. Most of the conventional DNA barcode sequences contain the whole information of a given barcoding gene. Most of the sequence information does not vary and is uninformative for a given group of taxa within a monophylum. We suggest here a method that reduces the amount of noninformative nucleotides in a given barcoding sequence of a major taxon, like the prokaryotes, or eukaryotic animals, plants, or fungi. The actual differences in genetic sequences, called single nucleotide polymorphism (SNP) genotyping, provide a tool for developing a rapid, reliable, and high-throughput assay for the discrimination between known species. Here, we investigated SNPs as robust markers of genetic variation for identifying different pigeon species based on available cytochrome c oxidase I (COI) data. We propose here a decision tree-based SNP barcoding (DTSB) algorithm where SNP patterns are selected from the DNA barcoding sequence of several evolutionarily related species in order to identify a single species with pigeons as an example. This approach can make use of any established barcoding system. We here firstly used as an example the mitochondrial gene COI information of 17 pigeon species (Columbidae, Aves) using DTSB after sequence trimming and alignment. SNPs were chosen which followed the rule of decision tree and species-specific SNP barcodes. The shortest barcode of about 11 bp was then generated for discriminating 17 pigeon species using the DTSB method. This method provides a sequence alignment and tree decision approach to parsimoniously assign a unique and shortest SNP barcode for any known species of a chosen monophyletic taxon where a barcoding sequence is available. [ABSTRACT FROM AUTHOR]

The three species in the genus Claravis (Aves: Peristerinae) are unique among members of the small New World ground-dove clade. All three species inhabit forested areas rather than open scrubby habitat, and exhibit obvious sexual dichromatism. However, the phylogenetic relationships within Claravis remain unknown. The only molecular phylogenetic study to include more than one species of Claravis indicated the genus is paraphyletic. Here we include molecular data from all three Claravis species, including sequences from a museum skin of the previously unsampled Claravis geoffroyi (purple-winged ground-dove). Using both mitochondrial and nuclear loci, we estimate phylogenies and divergence times for the small New World ground-dove clade. We also use ancestral state reconstruction methods to infer the evolution of male blue plumage (and thus sexual dimorphism) in the clade. As in the previous study we recover Claravis as a paraphyletic group, but with Claravis geoffroyi as the sister species to Claravis mondetoura (maroon-chested ground-dove). This result has important implications for the evolutionary history of the small New World ground-dove clade. In particular, we recover multiple independent transitions between the monomorphic and dimorphic plumage states, which perhaps indicates sexual dimorphism arose twice in the group. [ABSTRACT FROM AUTHOR]

In this study, the foot and hind limb bones of pigeons and quails were measured morphometrically. Additionally, microscopic classifications of the muscles affecting the foot and digit joints were made. For the macroscopic inspection, 40 birds were used, including 20 adult quails (10 males, 10 females) and 20 adult pigeons (10 males, 10 females). Diethyl ether was inhaled to anaesthetize the animals. The poultry animals were put under anaesthesia, and radiographic pictures of their left feet were obtained individually. DAP measurements were performed separately from the images taken with the Image J program. Then, they were euthanized by cervical dislocation under diethyl ether anaesthesia. The right legs of the euthanized animals were preserved in a 10% neutral formalin solution for histology procedures just after the legs were dissected from the trunk. Morphometric measurements of bone lengths were made in accordance with the measurement points specified by von den Driesch. After fixation for histological examination, routine tissue follow-up was performed and the tissues were embedded in paraffin. The presence of SO-type I, FG-type IIb and FOG-type IIa in 4-5 μ sections taken from paraffin blocks was demonstrated using the indirect streptavidin-biotin-complex method from immunohistochemical methods. The result of our study was statistically evaluated at p < 0.05 and p < 0.001 levels. The length of the hallux, the articulation point to the TMT and the fibre arrangements in the two flexor group muscles showed that the hind limbs and feet of the pigeons had a more favourable anatomical and histological structure for the perching movement., (© 2023 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.)

Shahan et al. (2006) found that the relative rate of pigeons' pecking on two observing responses (i.e., responses that only produced an S+ or stimulus correlated with primary reinforcement) was well described by the relative rate of S+ delivery. Researchers have not evaluated the effects of S+ delivery rate in a concurrent observing response procedure with human subjects, so the necessary procedural modifications for studying the effects of conditioned reinforcement on human choice remain unclear. The purpose of the current study was to conduct an additive component analysis of modifications to the procedures of Shahan et al. (2006). We evaluated the additive effects of introducing response cost, a changeover response, and ordinal discriminative stimuli on correspondence with the results of Shahan et al. and the quality of fits of the generalized matching equation. When our procedures were most similar to those of Shahan et al., we observed low rates of observing and indifference between the two observing responses. For the group of subjects with whom all three additive components were included, we obtained the highest level of sensitivity to relative rate of S+ delivery, but the slope and R 2 of our fits of the generalized matching equation were still much lower than those obtained by Shahan et al. Potential reasons for these discrepancies, methods of resolving them, and implications for future research are discussed., (© 2023 Society for the Experimental Analysis of Behavior.)

The simultaneous matching-to-sample procedures that are widely used to study stimulus equivalence in human participants have generally been unsuccessful in animals. However, functional equivalence classes have been demonstrated in pigeons and sea lions using a concurrent repeated reversal discrimination procedure. In this procedure, responding to one set of stimuli is reinforced but responding to a different set is not and the set associated with reinforcement is changed with multiple reversals during the experiment. The experiments reported here were designed to assess whether functional equivalence classes could be demonstrated in rats using similar techniques. Rats were initially trained with two sets of olfactory stimuli (six odors/set). Following many reversals, probe reversal sessions were conducted in which rats were exposed to a subset of the members of each set and, later in the session, the withheld stimuli were introduced. Responding to these delayed probe trials in accord with the reversed contingencies constituted transfer of function. There was some evidence of transfer in Experiment 1, but the effects were relatively weak and variable. Experiment 2 introduced procedural changes and found strong evidence of transfer of function consistent with the formation of functional equivalence classes. These procedures offer a promising strategy to study symbolic behavior in rodents., (© 2023 Society for the Experimental Analysis of Behavior.)

Fruit doves ( Ptilinopus) constitute a genus of small to medium-sized, brightly colored arboreal birds, whose diets consist entirely of fruit. Little is known about the behavior of fruit doves because most species inhabit dense forests and are difficult to observe in the wild. This study describes the parental behavior of Jambu fruit dove pairs ( Ptilinopus jambu) in a captive breeding program at the Saint Louis Zoo. Continuous video recordings were made of three pairs which raised a total of eight squabs over 2 years; daily rates of parental and squab behaviors were quantified. Overall, females were present at the nest, brooded their squabs, pecked, and attempted feedings more often than males. Parents also cared for their squabs at different times throughout the day. Males fed and brooded squabs during the middle of the day, while females fed throughout the day and brooded in the morning, evening, and overnight. Feeding rates were lower than those described for seed-eating doves (Columbinae), with hours between consecutive feedings, and squabs rarely begged before feeding events. Most squab behaviors involved initiating or terminating brooding and self-preening. These behaviors increased as squabs approached fledging, and coincided with a shift from full to partial brooding, and a decrease in parental allopreening. Older squabs also initiated feeding less frequently. Together, these data provide the first description of parental behavior in a Ptilinopus fruit dove. The results of this study may help improve captive breeding efforts, which are likely to become increasingly important for future conservation and reintroduction programs. Zoo Biol. 35:120-127, 2016. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Aim The geographical expansion of white-winged doves ( Zenaida asiatica) in North America has attracted the attention of biologists and sportsmen because of their recreational and aesthetic value; however, data on factors driving the spatial spread of this species are lacking. We examined spatial and temporal patterns of range expansion for white-winged doves along the northern edge of their geographical range from 1979 to 2007 and used a dynamic occupancy model to estimate when and where doves would be found along an expansion gradient. Location Southern half of the USA. Methods We modelled spatial variation in the range expansion of white-winged doves from 1979 to 2007 using data from the North American Breeding Bird Surveys ( BBS) and distance from initial population centre, area of urban land cover, and ecoregion. We used a robust design occupancy analysis to estimate species expansion rate based on a model set grounded in broad-scale conditions likely to drive dove distribution. We evaluated our best fitting model (using Akaike's information criterion adjusted for small sample size) by comparing estimates to actual observations in 1993 and 2007 using area under the curve ( AUC) metrics from receiver-operating characteristic plots. Results Our spatial distribution model indicated that range expansion of white-winged doves was primarily influenced by distance from the core population centre, with additive effects of ecoregion and land cover. In 1979, white-winged doves were present in 12% of survey locations, whereas presence increased to 41% by 2007. Across all ecoregions, urban land cover was positively related to probability of occupancy. We evaluated our model for 1993 and 2007 by comparing derived occupancy estimates to sightings of white-winged doves within our sample hexagons using BBS survey data. Based on high AUC statistics (> 0.85), we concluded that our model was useful for accurately predicting range expansion. Main conclusions Estimating occurrence and range expansion of white-winged doves and other expanding/invasive avian species at large spatial scales can be effectively conducted using BBS data. Using these nationwide, long-term survey data to relate expansion to a suite of conditions likely to drive population dynamics is an effective approach to developing predictive models of range expansion. [ABSTRACT FROM AUTHOR]

Effects of delays of reinforcement on zebrafish behavior were examined following training with immediate reinforcement. The delay was either signaled by an exteroceptive stimulus present for the entire delay period (fully signaled), signaled briefly only at delay onset (partial signal), or without a stimulus (unsignaled). Unsignaled delays consistently resulted in low response rates. Fully signaled delays resulted in higher response rates than unsignaled delays when the delay was 3 s, but this difference in response rates disappeared at 6-s delays. Partially signaled delays were less effective in maintaining responding than fully signaled delays, but more effective than unsignaled delays, although these results were only suggestive. These results indicate that stimulus changes that occur during delays to reinforcement have similar effects with zebrafish as with other species, but also that responding of zebrafish has a relatively low tolerance to the delay duration. A vast majority of experiments examining zebrafish behavior suggests that the fish have potential to serve as an interface between biological and behavioral science, but this may not be the case in some research areas involving delays, such as delay discounting., (© 2022 Society for the Experimental Analysis of Behavior.)

The decline in melatonin secretion with age seems to be one of the major reasons for increased sleep disruption in older animals. Previously, we showed that the administration with melatonin or its precursor, tryptophan, improved activity/rest rhythms in aged individuals. Here, it was evaluated the effect of a 10-day consumption of a Jerte Valley cherry-based nutraceutical product (patent no. ES2342141B1), which contains high levels of tryptophan, serotonin and melatonin, on the activity/rest rhythms of young and old rats ( Rattus norvegicus) and ringdoves ( Streptopelia risoria) as representatives of animals with nocturnal and diurnal habits, respectively, and its possible relationship with the serum levels of melatonin and glucose. Total diurnal and nocturnal activity pulses were logged at control, during, and up to 3 days after the treatment. Melatonin and glucose were measured with ELISA and testing kits respectively. In both young and old rats, the intake of the cherry nutraceutical decreased diurnal activity, whereas nocturnal activity increased. The opposite effect was observed for ringdoves. The treatment increased the circulating levels of melatonin in both species and restored the amplitude of the activity rhythm in the old animals to that of the non-treated young groups. The consumption of a Jerte Valley cherry-based nutraceutical product may help to counteract the impaired activity/rest rhythm found in aged animals. [ABSTRACT FROM AUTHOR]

Aim World-wide declines in large-bodied frugivores may change seed deposition patterns dramatically if body mass influences seed dispersal-related traits, such as dispersal distance. We quantified movement patterns and seed dispersal distances by Hemiphaga novaeseelandiae (kereru), the fifth-largest surviving pigeon world-wide. We then reviewed how body mass affects seed dispersal distance among fruit-eating birds globally. Location Taranaki and Canterbury, New Zealand. Methods We radio-tracked 24 kereru, following each bird continuously for up to 8.5 h, for a total of 43 tracking-days during the peak fruiting season ( February- April). We estimated seed dispersal distances for three fleshy-fruited species using a mechanistic model based on kereru movements and seed retention times. We analysed global data for volant avian frugivores to determine the effect of body mass on time spent in fruiting trees, seed retention time, and dispersal distance. Results Kereru were highly sedentary, with an average of 32 ± 39 (mean ± SD) minutes and maximum of 315 minutes between flights. Kereru flew a mean of 77 ± 159 m and maximum of 1457 m in a single flight. They dispersed 66-87% of ingested seeds away from the parent plant. Mean seed dispersal distances for Beilschmiedia tawa, Vitex lucens and Pseudopanax arboreus were 95, 98 and 61 m, respectively, with all species dispersed up to 1469 m. For all three species, 79-88% of seeds were dispersed < 100 m and < 1% were dispersed > 1 km from the parent plant. Globally, both the mean time spent in fruiting trees and seed retention time increased with increasing frugivore body mass. However, retention time increased faster, and therefore the dispersal distance and percentage of seeds moved away from the parent increased with body mass. Main conclusions Despite sedentary behaviour, kereru disperse many seeds away from the parent plant due to their even longer gut passage time, a function of their large size. Large-bodied frugivores are disproportionately important as dispersers not only because they can swallow larger fruits, but also because they are more likely to deposit seeds away from the parent plant and at greater distances. [ABSTRACT FROM AUTHOR]

Understanding factors related to the range expansion trajectory of a successful invasive species may provide insights into environmental variables that favour additional expansion or guide monitoring and survey efforts for this and other invasive species. We examined the relationship of presence and abundance of Eurasian Collared Doves Streptopelia decaocto to environmental factors using recent data from the North American Breeding Bird Survey to understand factors influencing its expansion into the continental USA. A zero-inflated Poisson (ZIP) model was used to account for excess zero observations because this species was not observed on the majority of survey routes, despite its large geographical range. Model fit was improved when we included environmental covariates as compared with the null model, which only included distance from the route where this species was first observed. Probability of zero count was positively related to the distance from the first route and road density and was inversely related to minimum temperature and distance to coast. Abundance of the species was positively related to road density and was inversely related to annual precipitation and distance to coast. Random intercept by land-cover type also improved model fit. Model fit was improved with the ZIP model over the standard Poisson model, suggesting that presence and abundance of this species are characterized by different environmental factors. However, overall low accuracy of model-predicted presence/absence and abundance with the independent validation dataset may indicate either that there are other explanatory factors or that there is great uncertainty in the species’ colonization process. Our large-scale study provides additional evidence that the range expansion of this species tends to follow human-altered landscapes such as road and agricultural areas as well as responding to general geographical features such as coastlines or thermal clines. Such patterns may hold true for other invasive species and may provide guidelines for monitoring and assessment activities in other invasive taxa. [ABSTRACT FROM AUTHOR]

Most tropical trees produce fleshy fruits that attract frugivores that disperse their seeds. Early demography and distribution for these tree species depend on the effects of frugivores and their behavior. Anthropogenic changes that affect frugivore communities could ultimately result in changes in tree distribution and population demography. We studied the frugivore assemblage at 38 fruiting Elmerrillia tsiampaca, a rain forest canopy tree species in Papua New Guinea. Elmerrillia tsiampaca is an important resource for frugivorous birds at our study site because it produces abundant lipid-rich fruits at a time of low fruit availability. We classified avian frugivores into functional disperser groups and quantified visitation rates and behavior at trees during 56 canopy and 35 ground observation periods. We tested predictions derived from other studies of plant–frugivore interactions with this little-studied frugivore assemblage in an undisturbed rain forest. Elmerrillia tsiampaca fruits were consumed by 26 bird species, but most seeds were removed by eight species. The most important visitors (Columbidae, Paradisaeidae and Rhyticeros plicatus) were of a larger size than predicted based on diaspore size. Columbidae efficiently exploited the structurally protected fruit, which was inconsistent with other studies in New Guinea where structurally protected fruits were predominantly consumed by Paradisaeidae. Birds vulnerable to predation foraged for short time periods, consistent with the hypothesis that predator avoidance enhances seed dispersal. We identified seven functional disperser groups, indicating there is little redundancy in disperser groups among the regular and frequent visitors to this tropical rain forest tree species. [ABSTRACT FROM AUTHOR]

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The article discusses the molecular identification of two endangered pigeon species (Columbidae) in Canary Islands. The distribution and diet of the pigeons are analyzed using faecal samples to identify the target species. It states that pigeon species such as C. bollii and C. junoniae share the same features body sizes and food resources. Both endemic pigeon species in the Canary Islands which share the same laurel forest areas were successfully identified by the HaeIII restriction profiles of PCR-amplified products through faecal sampling. Furthermore, the pigeon species are said to be of conservation concern, but due to their arboreal habits and cautious nature, their ecology is poorly understood. [ABSTRACT FROM AUTHOR]

Cases of mast seeding, involving highly variable seed production synchronized over large geographic areas, provide dramatic examples of resource pulses that have been documented for most major world land masses. Here, we compare the dynamic behavior of two of these systems, with the goal of understanding differences in the long-term consequences of masting events to their respective communities. Responses to mast events in deciduous oak forests in eastern North America are characteristically complex and of low resilience. That is, each event produces long-lasting cascading effects in the community, ultimately influencing not only seed consumers such as rodents and deer, but also the parasites and prey of those consumers, diseases transmitted by those parasites, and outbreaks of insect herbivores. In contrast, despite more extreme resource pulsing in New Zealand Nothofagus forests, responses to mast events there are less complex and more resilient, i.e., producing only short-term (<2 years), smoothly damped, numerical responses by a few species, except after (rare) ‘double-mast’ events in consecutive years. A detailed examination of the two systems suggests some tentative explanations for the strongly contrasting dynamics of these systems. Firstly, the higher number of species involved in North America seems to reduce resilience by increasing food chain length, lags, and alternative prey, all of which increase the dynamic complexity compared with that in New Zealand. Secondly, lack of a shared evolutionary history among species did not necessarily reduce resilience. Some exotic species showed well-damped fluctuations (e.g., stoats ( Mustela erminea L.) in New Zealand), while other exotics showed complex dynamics (e.g., gypsy moths ( Lymantria dispar L.) in North America). Thirdly, recent extinctions of species such as the passenger pigeon ( Ectopistes migratorius L.), once the dominant acorn predator in eastern North American forests, have likely produced qualitative changes in system dynamics in both communities. Fourthly, the North American community has more lags and hysteresis, which probably contribute to the greater dynamic complexity in eastern North America than in New Zealand Nothofagus forests. However, positive feedback loops present in North America seem to have little influence on system dynamics. Because the massive perturbations induced by masting events are major recurring challenges to an ecosystem, disentangling the causes of different system responses is likely to lead us to a better understanding of ecosystem function, resilience and stability. [ABSTRACT FROM AUTHOR]

The article examines the response of birds to exurban development in a southwestern savanna. Birds in grasslands and savannas in southeastern Arizona that were grazed by livestock were counted. The richness of species and the abundance of bird were higher in exurban neighborhoods than in landscapes that are undeveloped and independent of livestock grazing. The response to exurban development was evident among doves, quail, hummingbirds, aerial insectivores, and some ground-foraging sparrows. Livestock grazing effects were minor and mostly involved birds with requirements for tall ground cover of the lack of it. The results of the study suggest that the influence of exurban development on the abundance of birds and variety was greatest at the lowest housing densities.

We investigated whether the New Zealand pigeon Hemiphaga novaeseelandiae (Columbidae) exhibits size-based preferences for fruits. We tested the hypothesis that in small-fruited species, pigeons would prefer larger fruits, but in larger-fruited species, this preference would reverse as the pigeons become increasingly limited by their gape size. We collected undispersed fruits and bird-dispersed seeds of 10 plant species, some over several sites or years (13 datasets in total). We estimated the fruit size of dispersed seeds by fitting regressions of fruit diameter to seed diameter in intact fruits. We were able to predict fruit diameter from seed diameter in 12 of the 13 populations, although the relationship was stronger in single-seeded species than in multi-seeded species. Seven of the 12 populations tested showed a significant difference in seed diameter among undispersed and dispersed seeds. However, our results showed no consistent pattern in fruit size preference by the New Zealand pigeon and did not support our hypothesis. The large-bodied New Zealand pigeon is generally not gape limited and fruit size preferences appear to be independent of mean fruit size. [ABSTRACT FROM AUTHOR]

Allocation of carotenoid pigments, either through nutritional provisioning or from endogenous reserves, makes up a form of non-genetic parental investment to progeny that may contribute to fitness. To date, carotenoids derived from endogenous reserves have been acknowledged as important vectors in translating only avian female phenotype and environmental conditions experienced prior to laying. Here, we show that in columbidae, crop milk delivered by both parents may provide chicks with a large amount of endogenous carotenoids at the postzygotic stage. Major carotenoids were xanthophylls and beta-carotene, but their concentrations showed large variation among individuals. Interestingly, a large amount of this variation was explained by brood identity, suggesting either environmental influences and/or phenotypic influences on a parent's ability to transfer these biomolecules. Our study therefore illuminates a potential new route for endogenous carotenoid-mediated parental effects. [ABSTRACT FROM AUTHOR]

Aim The study of the spatial dynamics of invasive species is a key issue in invasion ecology. While mathematical models are useful for predicting the extent of population expansions, they are not suitable for measuring and characterizing spatial patterns of invasion unless the probability of detection is homogeneous across the distribution range. Here, we apply recently developed statistical approaches incorporating detection uncertainty to characterize the spatial dynamics of an invasive bird species, the Eurasian collared dove ( Streptopelia decaocto). Location France. Methods Data on presence/absence of doves were recorded from 1996 to 2004 over 1045 grid cells (28 × 20 km) covering the entire country. Each grid cell included five point counts spaced along a route, which was visited twice a year, allowing for an estimation of detection probability. Each route was assigned to one of six geographical regions. We used robust design occupancy analysis to assess spatial and temporal variation in parameters related to the spatial dynamics of the species. These parameters included occupancy rate, colonization and local extinction probabilities. Our inference approach was based on the selection of the most parsimonious model among competitive models parametrized with conditional probabilities. Results The probability of detecting the presence of doves on a given route was high. However, we found evidence to incorporate detection uncertainty in inference processes about spatial dynamics, since detection probability was neither perfect (i.e. it was < 1), nor constant over space and time. Results showed a clear positive trend in occupancy rate over the study period, increasing from 55% in 1996 to 76% in 2004. In addition, occupancy rate differed among regions (range: 37–79%) and further analysis showed that colonization probability by region was positively related to occupancy rate. Finally, local extinction probability was lower than colonization probability and showed a tendency to decrease over the study period. Main conclusions Our results emphasize the importance of estimating detection probabilities in order to draw proper inferences about the spatial and temporal dynamics of the invasion pattern of the collared dove. In contrast to the perceived spatial dynamics from national atlas surveys, we provide evidence that the range of this species is currently increasing in France. Other results, such as regional specificity in colonization probabilities and time variation in local extinction are consistent with expectations from invasion and metapopulation theory. [ABSTRACT FROM AUTHOR]

Like lactating mammals, male and female ring dove parents increase their food consumption to meet the energetic challenges of provisioning their young. To clarify the neurochemical mechanisms involved, the present study investigated the relationship between parental hyperphagia and changes in activity of the potent orexigen neuropeptide Y (NPY) in the hypothalamus of breeding doves. Changes in NPY-immunoreactive (NPY-ir) cell numbers in the tuberal hypothalamus of male and female doves were examined by immunocytochemistry at six stages of the breeding cycle. Parallel NPY mRNA measurements were recorded in mediobasal hypothalamus (which includes the tuberal hypothalamus) by semiquantitative reverse transcription-polymerase chain reaction using 18S rRNA as the internal standard. NPY mRNA changes were also measured in the mediobasal hypothalamus of nonbreeding doves following intracranial administration of prolactin, an orexigenic hormone that is elevated in the plasma of parent doves, and in response to food deprivation, which mimics the negative energy state that develops in parents as they provision their growing young. NPY-ir cell numbers in the tuberal hypothalamus and NPY mRNA levels in the mediobasal hypothalamus were significantly higher in breeding males and females during the period of parental hyperphagia after hatching than during the late incubation period when food intake remains unchanged. In nonbreeding doves, food deprivation and prolactin treatment increased NPY mRNA in this region by two- to three-fold, which suggests that NPY expression is sensitive to hormonal and metabolic signals associated with parenting. We conclude that NPY synthesis is increased in the mediobasal hypothalamus during the posthatching period, which presumably supports increased NPY release and resulting parental hyperphagia. NPY-ir and mRNA were also high in the mediobasal hypothalamus prior to egg laying when food intake remained unchanged. Several lines of evidence suggest that this elevation in NPY supports the increased gonadal activity that accompanies intense courtship and nest building interactions in breeding doves. [ABSTRACT FROM AUTHOR]

Estimates of population trend for the interior subspecies of band-tailed pigeon (Patagioenas fasciata fasciata) are not available because no standardized survey method exists for monitoring the interior subspecies. We evaluated 2 potential band-tailed pigeon survey methods (auditory and call broadcast surveys) from 2002 to 2004 in 5 mountain ranges in southern Arizona, USA, and in mixed-conifer forest throughout the state. Both auditory and call-broadcast surveys produced low numbers of cooing pigeons detected per survey route (x̄ ≤ 0.67) and had relatively high temporal variance in average number of cooing pigeons detected during replicate surveys (CV > 161%). However, compared to auditory surveys, use of call-broadcast increased 1) the percentage of replicate surveys on which >1 cooing pigeon was detected by an average of 16%, and 2) the number of cooing pigeons detected per survey route by an average of 29%, with this difference being greatest during the first 45 minutes of the morning survey period. Moreover, probability of detecting a cooing pigeon was 27% greater during call broadcast (0.80) versus auditory (0.63) surveys. We found that cooing pigeons were most common in mixed-conifer forest in southern Arizona and density of male pigeons in mixed-conifer forest throughout the state averaged 0.004 (SE = 0.001) pigeons/ha. Our results are the first to show that call-broadcast increases the probability of detecting band-tailed pigeons (or any species of Columbidae) during surveys. Call-broadcast surveys may provide a useful method for monitoring populations of the interior subspecies of band tailed pigeon in areas where other survey methods are inappropriate. [ABSTRACT FROM AUTHOR]

The recent Eurasian collared-dove (Streptopelia decaocto, hereafter collared-dove) invasion of North America has raised concerns regarding its effects on native species, particularly mourning doves (Zenaida macroura). Our goal was to assess the potential for, and possible consequences of, foraging competition between mourning doves and collared-doves. We compared diet selection and measured degree of dietary overlap between the 2 dove species in a captive cafeteria experiment, and we measured aggression and competitive ability of these species in 3 captive competition experiments. We evaluated the effects of body size, temperature, and food distribution on aggression and competitive ability of both species, and we measured intraspecific aggression levels and competitive ability within each species. We found a high degree of dietary overlap between species; food preferences were similar between species, and Pianka's index of foreging-niche overlap was 0.95. Neither aggression nor competitive ability varied between species, however. Distribution of food in cafeteria experiments did not affect seed-preference results. Ambient temperature and body size of competitors had little effects on aggression or competitive ability of either species. Distribution of food in the environment affected aggression between species, however; aggression was greater in single (0.50 ± 0.10 interactions/min) than in multiple-patch (0.12 ± 0.02 interactions/min) trials. Collared-doves do not appear behaviorally more aggressive or competitively successful than mourning doves. Our results suggest that the potential for negative effects of collared-doves on mourning dove populations may be less than previously suspected, so control measures for collared doves may be unnecessary. However, competitive dynamics involving larger flocks of collared-doves and other potentially limiting resources must be considered. [ABSTRACT FROM AUTHOR]

The prevalence and density of infection with the haematozoan parasite Leucocytozoon marchouxi was studied in captive and free-living Pink Pigeons Columba mayeri on Mauritius between 1994 and 2002. Blood smears from adults, juveniles and squabs were screened. Overall prevalence of L. marchouxi was 30% and there were age class and year differences. Younger birds (≤ 1 year) were more often infected and had a higher density of infection than did older birds. High parasite levels were found in 6% of birds, all but one of which were less than 1 year old. Leucocytozoonosis has been recorded elsewhere in 20 out of 45 Pink Pigeons post-mortem and was the primary cause of death in 15 birds. However, we detected no significant difference in the survival of infected and uninfected birds examined in this study, suggesting that only subclinical infections were detected and any mortality was probably due to additional contributing factors such as concurrent disease and food shortages. A smaller sample of smears from other columbid species was collected to examine their role as reservoir hosts. The parasite was probably introduced to Mauritius with exotic columbids, which may be partially resistant, but the Pink Pigeon has acquired sufficient immunity now to be a maintenance host for the parasite. [ABSTRACT FROM AUTHOR]

Ring doves ( Streptopelia risoria) exhibit marked increases in food consumption and decreases in body weight when they are provisioning their young. This study examined changes in hypothalamic immunostaining for agouti-related peptide (AGRP), an endogenous melanocortin receptor antagonist and appetite stimulant, during the ring dove breeding cycle. Because prolactin is orexigenic in doves, and is elevated in blood at the onset of parental hyperphagia, we also explored the possibility that prolactin-induced hyperphagia is associated with AGRP changes. The numbers of AGRP-immunoreactive (ir) cells within the tuberal hypothalamus were maximal during the prelaying period of the breeding cycle but decreased dramatically during early incubation. AGRP-ir cell numbers began to increase again during late incubation and reached a peak during the early and late posthatching stages. Because posthatching elevations in AGRP-ir were temporally associated with marked elevations in parental food intake, and because AGRP is orexigenic in doves, these findings suggest that increased AGRP activity in the dove tuberal hypothalamus may contribute to parental hyperphagia. Rising prolactin secretion during late incubation and early posthatching may initiate this increase in AGRP-ir, since intracerebroventricular administration of prolactin significantly elevated food intake and AGRP-ir cell numbers in the tuberal hypothalamus of nonbreeding doves. Prolactin-induced elevations in AGRP-ir cell numbers persisted when the confounding effects of weight gain that accompany prolactin-induced hyperphagia in nonbreeding doves were eliminated by a food restriction procedure, thereby suggesting that prolactin can directly influence AGRP activity under neutral energy state conditions. [ABSTRACT FROM AUTHOR]

Since 1968, Turtle Doves Streptopelia turtur in Britain have declined in number by 70% and in breeding range by at least 25%. This study was undertaken during the 1998–2000 breeding seasons at two sites in East Anglia to examine habitat use and foraging ecology. Home ranges of radiotagged Turtle Doves were 0.3–1130 ha in size and contained more woodland than expected from availability. Radiotagged birds undertook foraging trips of up to 10 km. Turtle Doves were recorded feeding primarily at ‘man-made’ sites (i.e. spilt grain, animal feed and grain stores) and were only infrequently recorded feeding at ‘natural’ sites. Diet analysis showed that wheat and rape seed averaged 61% of the seeds eaten by Turtle Doves. This contrasts with a study undertaken in Britain in the 1960s, when the seeds of wild plants (weeds) constituted over 90% of those eaten, with wheat and rape seeds making up only 5%. The current arrangements for set-aside and agri-environmental schemes provide a framework for the establishment and maintenance of weed-rich areas on farmland as a source of wild food. [ABSTRACT FROM AUTHOR]

Examines the importance of saguaro fruit for desert dove species in the U.S. Description of the saguaro cactus; Production of water and nutrient source for desert animals; Incorporation of saguaro carbon into dove tissues.

The influence of maternal versus dietary sources of polychlorinated biphenyls (PCBs) deposited to eggs of ring doves (Streptopelia risoria) was investigated. Mature birds that lay a clutch of two eggs every 12 to 15 d were fed a diet of pellets spiked with 2,2′,4,4′,5,5′-hexacholorobiphenyl (unlabelled isotope designated as [12C]PCB153) for 25 d. The birds were subsequently switched to a diet containing isotopically labeled [U-13C12]PCB153 at similar concentrations for an additional 63 d. The toxicokinetics of [12C]PCB153 and [13C]PCB153 were followed in egg and carcass samples with time. Isotopic ratios of PCB153 in yolk lipids were identical to those in carcass lipids after introduction of diet 2, and they did not resemble those of the food at the time of egg formation. The data indicate that the PCB composition of eggs directly reflects the composition of maternal tissues, not the diet, at the time of yolk formation. Egg yolk:carcass lipid concentration ratios for the two isotopes were significantly less than one, averaging 0.33 ± 0.02 (mean 6 standard error). Lipid normalized egg:maternal tissue contaminant concentration ratios for persistent organochlorine chemicals in the literature were reviewed for other avian species. The results provide a preliminary data set that suggests egg:maternal tissue contaminant concentration ratios vary among species, particularly among species that invest different quantities of lipids to a clutch of eggs. The results support the hypothesis that dilution of contaminants in egg lipids relative to maternal lipids is related to the reproductive strategy employed by the species. [ABSTRACT FROM AUTHOR]